#!/bin/sh

# run from directory where this script is
cd `dirname $0`
EXAMPLE_DIR=`pwd`

# check whether ECHO has the -e option
if test "`echo -e`" = "-e" ; then ECHO=echo ; else ECHO="echo -e" ; fi

$ECHO
$ECHO "$EXAMPLE_DIR : starting"
$ECHO
$ECHO "This example shows how to use pw.x and turbo_davidson.x"
$ECHO "to calculate the absorption spectrum of the CH4 molecule."

# set the needed environment variables
. ../../../environment_variables

# required executables and pseudopotentials
BIN_LIST="pw.x turbo_davidson.x"
PSEUDO_LIST="H.blyp-vbc.UPF C.blyp-mt.UPF"

$ECHO
$ECHO "  executables directory: $BIN_DIR"
$ECHO "  pseudo directory:      $PSEUDO_DIR"
$ECHO "  temporary directory:   $TMP_DIR"
$ECHO
$ECHO "  checking that needed directories and files exist...\c"

# check for directories
for DIR in "$BIN_DIR" "$PSEUDO_DIR" ; do
    if test ! -d $DIR ; then
        $ECHO
        $ECHO "ERROR: $DIR not existent or not a directory"
        $ECHO "Aborting"
        exit 1
    fi
done
for DIR in "$TMP_DIR" "$EXAMPLE_DIR/results" ; do
    if test ! -d $DIR ; then
        mkdir $DIR
    fi
done
cd $EXAMPLE_DIR/results

# check for executables
for FILE in $BIN_LIST ; do
    if test ! -x $BIN_DIR/$FILE ; then
        $ECHO
        $ECHO "ERROR: $BIN_DIR/$FILE not existent or not executable"
        $ECHO "Aborting"
        exit 1
    fi
done
$ECHO " done"

# check for pseudopotentials
for FILE in $PSEUDO_LIST ; do
    if test ! -r $PSEUDO_DIR/$FILE ; then
       $ECHO
       $ECHO "Downloading $FILE to $PSEUDO_DIR...\c"
            $WGET $PSEUDO_DIR/$FILE $NETWORK_PSEUDO/$FILE 2> /dev/null
    fi
    if test $? != 0; then
        $ECHO
        $ECHO "ERROR: $PSEUDO_DIR/$FILE not existent or not readable"
        $ECHO "Aborting"
        exit 1
    fi
done
$ECHO " done"

# how to run executables
PW_COMMAND="$PARA_PREFIX $BIN_DIR/pw.x $PARA_POSTFIX"
TURBO_DAVIDSON_COMMAND="$PARA_PREFIX $BIN_DIR/turbo_davidson.x $PARA_POSTFIX"
$ECHO
$ECHO "  running pw.x as:              $PW_COMMAND"
$ECHO "  running turbo_davidson.x as:  $TURBO_DAVIDSON_COMMAND"
$ECHO "  running turbo_spectrum.x as:  $TURBO_SPECTRUM_COMMAND"
$ECHO

# clean TMP_DIR
$ECHO "  cleaning $TMP_DIR...\c"
rm -rf $TMP_DIR/*
$ECHO " done"

PREFIX='CH4'

# self-consistent calculation
cat > $PREFIX.scf.in << EOF
 &control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='$PREFIX'
    pseudo_dir = '$PSEUDO_DIR/'
    outdir='$TMP_DIR/'
 /
 &system
    ibrav = 1,
    celldm(1) = 20,
    nat = 5,
    ntyp = 2,
    ecutwfc = 25,
    ecutfock = 25,
    nbnd = 20,
    input_dft = 'B3LYP'
 /
 &electrons
    conv_thr =  1.0d-10
 /
ATOMIC_SPECIES
H  1.008  H.blyp-vbc.UPF
C 12.011  C.blyp-mt.UPF
ATOMIC_POSITIONS {angstrom}
C   0.000000000   0.000000000   0.000000000
H   0.642814093   0.642814093   0.642814093
H  -0.642814093  -0.642814093   0.642814093
H   0.642814093  -0.642814093  -0.642814093
H  -0.642814093   0.642814093  -0.642814093
K_POINTS {gamma}
EOF
$ECHO "  Running the SCF calculation for $PREFIX..."
$PW_COMMAND < $PREFIX.scf.in > $PREFIX.scf.out
$ECHO " done"


# Perform the linear-response calculation
cat > $PREFIX.tddfpt.in << EOF
 &lr_input
   prefix = '$PREFIX',
   outdir = '$TMP_DIR/',
   restart = .false.
 /
 &lr_dav
   d0psi_rs = .true.
   num_eign = 10,
   num_init = 20,
   num_basis_max = 80,
   residue_conv_thr = 1.0D-4,
   start  = 0.0,
   finish = 1.5,
   step   = 2.0D-4,
   broadening = 0.005,
   reference = 0.5,
   p_nbnd_occ  = 4,
   p_nbnd_virt = 15,
   poor_of_ram  = .false.
   poor_of_ram2 = .false.
/
EOF
$ECHO "  Running the TDDFPT calculation for $PREFIX..."
$TURBO_DAVIDSON_COMMAND < $PREFIX.tddfpt.in > $PREFIX.tddfpt.out
$ECHO " done"
